package vectordb;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.CompletableFuture;
import java.util.stream.Collectors;

/**
 * Milvus 向量数据库实现
 */
public class MilvusVectorDB implements VectorDB {
    private String host;
    private int port;
    private String username;
    private String password;
    private boolean secure;
    private boolean initialized;
    private MilvusClient client;

    /**
     * Milvus 客户端接口
     * 这是一个内部接口，用于抽象 Milvus 客户端的操作
     * 在实际实现中，需要使用具体的 Milvus Java SDK
     */
    public interface MilvusClient {
        CompletableFuture<Void> connect();
        CompletableFuture<Boolean> hasCollection(String collectionName);
        CompletableFuture<Void> createCollection(String collectionName, int dimension, Map<String, String> metadataFields);
        CompletableFuture<Void> dropCollection(String collectionName);
        CompletableFuture<Void> insert(String collectionName, List<VectorDocument> documents);
        CompletableFuture<List<VectorSearchResult>> search(String collectionName, double[] queryVector, int limit, String filter);
        CompletableFuture<Long> count(String collectionName);
        CompletableFuture<Void> delete(String collectionName, List<String> ids);
        CompletableFuture<Void> close();
    }

    /**
     * Milvus 配置类
     */
    public static class MilvusConfig {
        private String host;
        private int port;
        private String username;
        private String password;
        private boolean secure;

        public MilvusConfig(String host, int port) {
            this.host = host;
            this.port = port;
            this.secure = false;
        }

        public MilvusConfig(String host, int port, String username, String password) {
            this.host = host;
            this.port = port;
            this.username = username;
            this.password = password;
            this.secure = false;
        }

        public MilvusConfig(String host, int port, String username, String password, boolean secure) {
            this.host = host;
            this.port = port;
            this.username = username;
            this.password = password;
            this.secure = secure;
        }

        public String getHost() {
            return host;
        }

        public void setHost(String host) {
            this.host = host;
        }

        public int getPort() {
            return port;
        }

        public void setPort(int port) {
            this.port = port;
        }

        public String getUsername() {
            return username;
        }

        public void setUsername(String username) {
            this.username = username;
        }

        public String getPassword() {
            return password;
        }

        public void setPassword(String password) {
            this.password = password;
        }

        public boolean isSecure() {
            return secure;
        }

        public void setSecure(boolean secure) {
            this.secure = secure;
        }
    }

    /**
     * 创建一个新的 Milvus 向量数据库连接
     * 
     * @param config Milvus 配置
     */
    public MilvusVectorDB(MilvusConfig config) {
        this.host = config.getHost();
        this.port = config.getPort();
        this.username = config.getUsername();
        this.password = config.getPassword();
        this.secure = config.isSecure();
        this.initialized = false;
        
        // 在实际实现中，这里应该创建真正的 Milvus 客户端
        // 这里使用一个模拟实现
        this.client = createMilvusClient();
    }

    /**
     * 创建 Milvus 客户端
     * 在实际实现中，这里应该返回真正的 Milvus 客户端
     * 
     * @return Milvus 客户端
     */
    private MilvusClient createMilvusClient() {
        // 这里应该使用实际的 Milvus Java SDK 创建客户端
        // 这里使用一个模拟实现
        return new MilvusClient() {
            @Override
            public CompletableFuture<Void> connect() {
                return CompletableFuture.completedFuture(null);
            }

            @Override
            public CompletableFuture<Boolean> hasCollection(String collectionName) {
                return CompletableFuture.completedFuture(false);
            }

            @Override
            public CompletableFuture<Void> createCollection(String collectionName, int dimension, Map<String, String> metadataFields) {
                return CompletableFuture.completedFuture(null);
            }

            @Override
            public CompletableFuture<Void> dropCollection(String collectionName) {
                return CompletableFuture.completedFuture(null);
            }

            @Override
            public CompletableFuture<Void> insert(String collectionName, List<VectorDocument> documents) {
                return CompletableFuture.completedFuture(null);
            }

            @Override
            public CompletableFuture<List<VectorSearchResult>> search(String collectionName, double[] queryVector, int limit, String filter) {
                return CompletableFuture.completedFuture(new ArrayList<>());
            }

            @Override
            public CompletableFuture<Long> count(String collectionName) {
                return CompletableFuture.completedFuture(0L);
            }

            @Override
            public CompletableFuture<Void> delete(String collectionName, List<String> ids) {
                return CompletableFuture.completedFuture(null);
            }

            @Override
            public CompletableFuture<Void> close() {
                return CompletableFuture.completedFuture(null);
            }
        };
    }

    @Override
    public CompletableFuture<Void> init() {
        if (this.initialized) {
            return CompletableFuture.completedFuture(null);
        }
        
        return this.client.connect()
                .thenApply(result -> {
                    this.initialized = true;
                    System.out.println("Connected to Milvus at " + this.host + ":" + this.port);
                    return null;
                })
                .exceptionally(e -> {
                    System.err.println("Failed to connect to Milvus: " + e.getMessage());
                    throw new RuntimeException("Failed to connect to Milvus", e);
                });
    }

    @Override
    public CompletableFuture<Void> createCollection(String collectionName, int dimension, Map<String, String> metadataFields) {
        return this.init()
                .thenCompose(result -> this.client.createCollection(collectionName, dimension, metadataFields))
                .thenApply(result -> {
                    System.out.println("Created collection: " + collectionName);
                    return null;
                })
                .exceptionally(e -> {
                    System.err.println("Failed to create collection: " + e.getMessage());
                    throw new RuntimeException("Failed to create collection", e);
                });
    }

    @Override
    public CompletableFuture<Boolean> hasCollection(String collectionName) {
        return this.init()
                .thenCompose(result -> this.client.hasCollection(collectionName))
                .exceptionally(e -> {
                    System.err.println("Failed to check collection: " + e.getMessage());
                    return false;
                });
    }

    @Override
    public CompletableFuture<Void> dropCollection(String collectionName) {
        return this.init()
                .thenCompose(result -> this.client.dropCollection(collectionName))
                .thenApply(result -> {
                    System.out.println("Dropped collection: " + collectionName);
                    return null;
                })
                .exceptionally(e -> {
                    System.err.println("Failed to drop collection: " + e.getMessage());
                    throw new RuntimeException("Failed to drop collection", e);
                });
    }

    @Override
    public CompletableFuture<Void> insert(String collectionName, List<VectorDocument> documents) {
        // 确保每个文档都有 ID
        documents.forEach(doc -> {
            if (doc.getId() == null || doc.getId().isEmpty()) {
                doc.setId(UUID.randomUUID().toString());
            }
        });
        
        return this.init()
                .thenCompose(result -> this.client.insert(collectionName, documents))
                .thenApply(result -> {
                    System.out.println("Inserted " + documents.size() + " documents into collection: " + collectionName);
                    return null;
                })
                .exceptionally(e -> {
                    System.err.println("Failed to insert documents: " + e.getMessage());
                    throw new RuntimeException("Failed to insert documents", e);
                });
    }

    @Override
    public CompletableFuture<List<VectorSearchResult>> search(String collectionName, double[] queryVector, int limit, String filter) {
        return this.init()
                .thenCompose(result -> this.client.search(collectionName, queryVector, limit, filter))
                .exceptionally(e -> {
                    System.err.println("Failed to search: " + e.getMessage());
                    return new ArrayList<>();
                });
    }

    @Override
    public CompletableFuture<Long> count(String collectionName) {
        return this.init()
                .thenCompose(result -> this.client.count(collectionName))
                .exceptionally(e -> {
                    System.err.println("Failed to count documents: " + e.getMessage());
                    return 0L;
                });
    }

    @Override
    public CompletableFuture<Void> delete(String collectionName, List<String> ids) {
        return this.init()
                .thenCompose(result -> this.client.delete(collectionName, ids))
                .thenApply(result -> {
                    System.out.println("Deleted " + ids.size() + " documents from collection: " + collectionName);
                    return null;
                })
                .exceptionally(e -> {
                    System.err.println("Failed to delete documents: " + e.getMessage());
                    throw new RuntimeException("Failed to delete documents", e);
                });
    }

    @Override
    public CompletableFuture<Void> close() {
        if (!this.initialized) {
            return CompletableFuture.completedFuture(null);
        }
        
        return this.client.close()
                .thenApply(result -> {
                    this.initialized = false;
                    System.out.println("Closed connection to Milvus");
                    return null;
                })
                .exceptionally(e -> {
                    System.err.println("Failed to close connection: " + e.getMessage());
                    throw new RuntimeException("Failed to close connection", e);
                });
    }
}